1. Field
The present invention relates to a method of fabricating a semiconductor device provided with a microscopic wiring pattern and the semiconductor device.
2. Related Art
A photolithography technique as one of semiconductor processing techniques includes a sidewall transfer process which provides a microscopic wiring pattern exceeding a limit of minimum patterning width of a resist film. For example, Japanese patent application publication, JP-A-2007-43156 discloses the following process through which a semiconductor device is fabricated. Firstly, a resist is patterned by an ordinary lithography technique, and a first film is etched so that core-forming patterns are formed at a predetermined pitch on a film to be processed. Next, a second film is formed along upper surfaces and side surfaces of the core-forming patterns and an exposed upper surface of the film to be processed, so as to have a predetermined film thickness. The second film is formed into the shape of a spacer so that the upper surfaces of the first film and film to be processed are exposed. Thereafter, the core-forming patterns are removed. As a result, a mask pattern of the spacer-shaped second film is obtained. The aforesaid film to be processed is processed using the obtained mask pattern of the second film, whereupon a microscopic wiring pattern can be formed.
In the above-described processing, the mask pattern formed by the above-described second film is spacer-shaped. Accordingly, side surfaces of the mask pattern facing the core-forming pattern are formed into a generally vertical shape, whereas side surfaces of the mask pattern located opposite the core-forming pattern has a generally rounded upper surface. The mask pattern accordingly has an unsymmetric section. When the mask pattern thus formed is used as a mask for the film to be processed, the unsymmetric shape of the mask pattern is transferred to the film to be processed. This results in a problem of a difference in the shape of the processed film.